Cu-poor and Cu-rich Cu(In,Ga)Se2 (CIGSe) absorbers were used as substrates for the chemical bath deposition of ultrathin CdS buffer layers in the thickness range of a few nanometers in order to make the CIGSe/CdS interface accessible by hard X-ray photo-emission spectroscopy. The composition of both, the absorber and the buffer layer as well as the energetics of the interface was investigated at room temperature and after heating the samples to elevated temperatures (200 °C, 300 °C and 400 °C). It was found that the amount of Cd after the heating treatment depends on the near surface composition of the CIGSe absorber. No Cd was detected on the Cu-poor surface after the 400 °C treatment due to its diffusion into the CIGSe layer. In contrast, Cd was still present on the Cu-rich surface after the same treatment at 400 °C.

The interface between CuInSe2 and i-ZnO as it is needed for new chalcopyrite concepts like superstrate and tandem solar cells is investigated with X-ray photoelectron spectroscopy. A specially developed preparation permits depth profiling of the underlying i-ZnO layer. Thereby, interfacial reactions are revealed by tracing the diffusion of Cu, In and Se through the i-ZnO. Formation of an In2O3 layer in between i-ZnO and CuInSe2 is shown for deposition temperatures of and . The experiments and thermodynamical ChemSage simulations indicate that this In2O3 layer already forms at during the first physical vapor deposition step. So far In2O3 formation was believed only to occur at temperatures above . An increase of Cu diffusion into the i-ZnO with deposition temperatures above can be explained with additional formation of ZnkIn2Ok+3 (k = 5 or k = 7) phases.

Spray deposition of thin films and coatings is a widely used manufacturing process owing to its low cost, versatility and simple implementation. The objective of the presented experiments was to investigate whether X-ray absorption measurements on solutes carried by aerosols are possible, and what count rates can be achieved depending on solution flow through and the resulting mass density in the interrogation volume. The investigated prototypical spray aerosol was InCl3dissolved in water or ethanol dispersedviaan ultrasonic nebulizer. InCl3spray is essential for the ion layer gas reaction process used for the deposition of In2S3buffer layers for highly efficient chalcopyrite solar cells. The discussed experiments demonstrate that measurements are possible, but that the achievement of good signal-to-noise ratios requires extended sampling times and concentrated solutions.